The present invention relates to a video display apparatus and method for use with, for example, a multiscan monitor. Multiscan monitors are designed to operate with input video signals having different horizontal frequencies and are used in color television receivers and computer monitors.
Currently there are computer monitors and television receivers which in addition to displaying an input video signal can display various monitor parameters that can be adjusted by displaying characters, numerals, graphics or a combination thereof. This capability to display the parameters to be adjusted is called "on-screen display" (hereinafter "OSD").
These video display devices having OSD capability are designed to allow the user to adjust parameters related to the video display operation. These parameters include the size and center position of the picture screen (raster) displayed upon under-scanning, the rotational distortion and the pincushion distortion of the screen resulting from geomagnetism, convergence, brightness, contrast and other parameters.
Such parameters are digitally adjusted by using operation keys used for controlling the adjustment amount of the elements. When these operation keys are used, graphs representing the current adjustments of the parameters are displayed and changed to reflect the new settings on the OSD portion of the display screen, thereby giving the user a visual feedback of the adjustment status.
FIG. 1 of the accompanying drawings is a front view of a monitor illustrating a manner in which the adjustment information is typically displayed on the display screen. Operation keys 31a, 31b, 32a, 32b used for controlling an increase and decrease of an adjustment amount are provided at fixed locations on the display apparatus. Further shown in FIG. 1, is an OSD Representation area displayed at a predetermined position of a display screen used to display the current adjustment settings using cursors 35 and 36 on bar graphs 33 and 34, respectively. By operating keys 31a, 31b and 32a, 32b the cursors 35 and 36 are respectively moved left or right corresponding to the adjustment being made, thereby giving the user a visual feedback.
The display apparatus of the computer system may receive video signals having various horizontal frequencies. For example, the video signals may have horizontal frequencies ranging from 15.75 kHz, which is similar to that of an ordinary television signal, to 31.5 Khz or 35 kHz used for high-definition display modes, or higher.
Since the horizontal linearity characteristics are changed depending on the horizontal frequency, an apparatus capable of receiving video signals having several horizontal frequencies, for example, a multiscan monitor, moves a raster position along the horizontal direction so that the picture is displayed at a position with an optimum horizontal linearity characteristic. Moreover, in order not to change the center position of a picture in response to the movement of the raster, such apparatus shifts the position of the picture relative to the raster to the center position thereof again.
The representation of the OSD described above is generally formed with reference to the synchronization signal. Therefore, when the raster position is moved as described above, the display position of the OSD representation is moved to the left or right on the picture screen in response to the change in the synchronization signal. In this case, since the respective OSD representations 33, 34 are displayed to be in alignment with the operation keys 31a, 31b and 32a, 32b, the movement of the raster will throw this alignment off to the point where the OSD representations 33, 34 may be moved off the screen, thereby preventing the user from seeing the full OSD representation.